ftp://ftp.pwg.org/pub/pwg/ipp/minutes/ipp-0597.txt
ftp://ftp.pwg.org/pub/pwg/ipp/minutes/ipp-0597.pdf
Additionally, the text version is attached below.
Don
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PWG Internet Printing Project Meeting Minutes
May 15, 1997
San Diego, CA
The meeting started on May 15, 1997 at 8:45 AM led by Carl-Uno Manros. The
attendees were:
* Ron Bergman - Data Products
* Lee Farrell - Canon
* Don Wright - Lexmark
* Scott Isaacson - Novell
* Jeff Copeland - QMS
* Bob Pentecost - HP
* Sylvan Butler - HP
* Tom Hastings - Xerox
* Harry Lewis - IBM
* William Wagner - Digital Products
* Robert Herriot - Sun
* Carl-Uno Manros - Xerox
* Keith Carter - IBM
* Stuart Rowley - Kyocera
* Peter Zehler - Xerox
* Steve Zilles - Adobe
* Randy Turner - Sharp
* Paul Moore - Microsoft
* J.K. Martin - Underscore
* Larry Masinter - Xerox
* Tony Liao - Vivid Image
* Stephen Holmstead
* Takami Kurono - Brother
* Jerry Hadsell - IBM
* Rick Yardumian - Xerox
* Xavier Riley - Xerox
* Zhi-hony Huang - Zenographics
* Gary Roberts - Ricoh
* Richard Schneider - Epson
* Robert Kline - TrueSpectra
* Patrick Powell - SDSU
* David Kellerman - Northlake Software
* Dave Kuntz - HP
* David Manchala - Xerox
Planned Agenda
Morning:
* Report of outcome from PWG MOD meeting May 14 (Scott Isaacson)
* Presentation on SWP - Paul Moore, Sylvan Butler
* CPAP Presentation - JK Martin
* HTTP/NG - Larry Masinter
* IPP Discussion - Bob Herriot, Randy Turner
Afternoon:
* Discussion about Prototyping efforts supporting the IPP protocol choices -
Peter Zehler
* Discussion of IPP Security - Carl-Uno Manros
Model Meeting Report
(Details will be published in model meeting minutes)
* Discussed whether model was meeting the goals and the requirements as
outlined in the
Requirements I-D.
* Discussed the job template attributes
* Discussed what does "best efforts" mean - new values: "shall" and "should"
* New draft to the IETF will take a little while due to re-formatting, etc.
Probably would
be 2 weeks before the next the draft.
Presentation by Paul Moore on SWP (Simple Web Printing)
(Charts and document are available on the PWG Web site.)
- Work has been underway for some time
- Enhanced and changed based upon feedback from IETF, etc
- It mandates
* Print submission protocol
- Command sequence
- data format
- encoding
- return values
* HTTP 1.1
* Security
- It suggests
* Client configuration
* Return URL
* Access Control
- It excludes
* job monitoring and control protocol
* printer discovery and client configuration
* print by reference
** Discussion on if HTTP is correct
** Discussion on use of Unicode versus a charset value for the text in the
headers
** Discussion on using HTTP chunking to determine the length of a job
** Should SWP send big-endian or little-endian? - big
- Management, discovery
* via HTML
* no client changes
* Not mandated
- Implementation planned to be similar to what Babak presented in February.
- Issues:
1) Enumerations versus keywords
2) Byte ordering
3) application/SWP
4) Mandate return URI - yes
5) What about unsupported attributes - ignore?
6) Adornments
7) Denial of service for anonymous users
---
8) Security
9) Is this to be an IETF standard?
10) TYPE as text versus 32-bit INT
11) Transport independent except length of print data
12) Charset - mandate unicode?
13) one post or multiple post (to get back job URI before whole job is posted)
14) What does the server do if the print job is too big?
15) Discovery of printers and their capabilities
16) Should we have SWP as well as a full-blown version to replace LPR. Should
one be a subset of the other?
IPP Model and Protocol Overview
Steve Zilles discussed briefly the material he presented at the IETF meeting in
Memphis.
CPAP - JK Martin
No presentation -- time was used for discussions.
** Wide ranging discussion on:
- what are we trying to do?
- what is wrong with LPD?
- are we trying to do everything through HTTP?
- is asynchronous notification a requirement?
- job submission versus status queries?
- is something like CPAP needed for Intranet solutions?
- how is policy reflected back to the client?
- should the protocol be self-describing?
- how are the MIBs (printer and job monitoring) related to IPP?
HTTP New Generation - Larry Masinter
- HTTP-NG is a promise, not yet real
- An effort to "fix" HTTP
- HTTP mission creep (too many projects hopping on the HTTP band-wagon)
- Need something to address the inefficiencies of HTTP
- More information from www.w3.org or ftp.parc.xerox.com/pub/masin
ter/http-ng.html
Lunch Break
Protocol Discussion - Bob Herriot
1) Encoding
SWP
HTTP-like application/IPP
CPAP
form-based
- attributes
* Herriot proposal for application/IPP
- document data
* swp (content length implicit)
* explicit doc #, chunk #
- operations
- responses (attributes and status)
2) 1 job operation or 2
A long discussion again was held on the issue of HTTP and the concept of using
something like SWP versus form-based upload.
The SWP proposal does not require the use of the browser in any way to perform
the
actual printing. The browser simply insures that the remote printer/server is
accessible
via HTTP and through firewalls, etc. that might be present.
The group in attendance voted to recommend to the entire working group that the
first
proposal should be based on HTTP/1.1 versus a newly created UDP or TCP/IP
protocol.
The results were 6 to 16 in favor of HTTP (Paul Moore of Microsoft voted twice.)
Resumed discussion on encoding.
A discussion was held on how to encode data. Embedded white space versus
including a
length value was discussed. Using embedded white space was perceived as being
more
difficult and time consuming that length. This results in an encoding of the
attributes that
looks like:
Length | Attribute-Name | Length | Attribute-Value
[00 08] JOB-NAME [00 0C] MSWORD-NOTES
First byte: Major Version (starts at 1)
Second byte: Minor Version (starts at 0)
Content Length includes all the attributes and not the length itself. The
minimum value is
0 which means no attributes.
Discussion on how to do multiple documents within a job
- multiple chunking
- meta-job
- doing the simple case and adding it via versioning
- multiple content-types: application/ipp
- using an attribute ("document count") to indicate multiple documents
** resolution: using "send-job" with single document count for the single
document per
job and use "create-job" with multiple document count to associate multiple
documents
Operation is an attribute and is the first attribute in the list.
Operations:
- create-job (create a job, data to follow, URI returned)
- send-data (data (attributes & pdl) for a previously sent create-job)
- print-job (attributes and print data all in one, URI returned)
- cancel
- get-jobs
- get attributes
- validate (attributes but no PDL, no URI returned)
What is the minimum implementation? Is an IPP implementation in a printer
required to
support multiple documents within a job? A printer could reject a create-job
operation
and force the client to use multiple print-job operations instead.
Resolution: Paul Moore will be writing a proposal for a level 1 conformance
(encoding,
operations and the transport) which will be a new version of the SWP document
within
the next couple of weeks. This draft will be made available to the group for
review
before publishing it as an IETF draft. It will be viewed and discussed at one
of the
conference calls.
Security
Carl-Uno Manros presented the security sub-group's work-in-progress and
status. His
charts will be available on the WEB/ftp server.
The combination of Digest Authentication and Transport Layer Security (=SSL3)
look
like a good combination for our specification. If a weaker security all that
is necessary
then Digest would be used; TLS if a stronger security is needed.
A new security negotiation "Simple Authentication and Session Layer" or SASL is
gaining mind share within the IETF.
Issues:
- object security works only with original MIME
- channel security protocols only work with a particular protocol
- if a new transfer protocol is used, there might not be a security means
available.
Goal is to have a new internet-draft available in the next two weeks.
Implementation Discussion
Can a special service provider register for a particular document type so that
it can be
"filtered" before it is printed? - yes, in the SWP case, via an ISAPI
extension, etc.
Documents
Work done by the protocol group will be reflected back into the model document
(new
operations, conformance.)
A directory document should be published in the next few weeks by Keith Carter.
Next meeting - June 25/26 in Nashua, NH.
The meeting adjourned at 6:10PM.
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*************************************************************
* Don Wright (don@lexmark.com) Lexmark International *
* Manager Strategic Alliances *
* 740 New Circle Rd Phone: 606-232-4808 *
* Lexington, KY 40511 Fax: 606-232-6740 *
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